This invention relates to an automotive safety device and particularly to an inflatable restraint module adapted for frontal or side impact protection featuring design and assembly improvements.
Inflatable restraint systems are now in widespread use in motor vehicles today. These systems incorporate a crash sensor which detects the onset of a vehicle collision and sends a triggering signal to the inflatable restraint module. A source of gas is activated in response to a crash signal to inflate a fabric air cushion which is presented to absorb impact energy of the occupant within the vehicle. Such inflatable restraint systems are found mounted to steering wheels for driver-side protection, or mounted to instrument panel structure to provide protection for front seat passengers. These systems have, been found to provide excellent occupant crash protection particularly when used with a belt type restraint system. Aiding in providing occupant protection for frontal impacts is the significant amount of deformable structure in the forward portion of the typical automobile. Moreover, todays crash sensors for frontal impact provide reliable crash signals in a time period permitting deployment of the inflatable restraint system. These advantages are not available when designing inflatable restraint systems for side impact collisions. Statistically, side impact collisions are more likely to cause significant injury or death as compared with frontal impacts with similar impact energy. This is attributable to the limited amount of vehicle structure between the occupant and the outside body structure subject to side impact collisions, and perhaps also due to human biomechanism. However, there is a belief that inflatable restraints for side impact collisions can provide significant benefits. Accordingly, there is increased emphasis in designing inflatable restraint systems for side impact protection.
Numerous designs of inflatable restraint systems are available today. Despite the tremendous effort exerted in optimizing the design of these devices, there is a continuing need to improve the manufacturability, cost, and reliability of the systems. Of significant importance is a reduction in the number of separate components which must be assembled to build the inflatable restraint system. The existence of a multiplicity of parts has a negative cost effect, both in terms of part fabrication and assembly. In addition, packaging size is of great importance in the design of today's motor vehicles. To make efficient use of packaging volume in the automobile it is desirable to reduce the overall size of an air bag module. Moreover, efforts to achieve benefits in these areas must not sacrifice the performance of the restraint system.
In accordance with this invention, an improved inflatable restraint module is provided which is particularly adapted for side impact protection applications, but may also be implemented in other environments such as front seat passenger-side applications. The module uses a molded plastic housing using a single piece clamshell construction, the housing contains a cushion and an inflator, and utilizes two major metal structural components, a retainer bracket, and a mounting bracket which interlock using bent tab fingers to retain the other module components together. The assembly is completed by mounting an inflator which is inserted through apertures in the mounting bracket and in the cushion, and into the interior of the retainer bracket. The inflator is secured with a single nut which loads the structural parts and cushion in compression. The inflatable restraint module in accordance with this invention requires only two simple metal parts. This concept allows a cylindrical inflator to be mounted in a side impact air bag module without the traditional reaction container which adds mass and creates packaging constraints. The module assembly according to this invention also allows for the interchangeable use of either a solid pyrotechnic or hybrid inflator. For the pyrotechnic inflator, the retainer bracket and mounting bracket further serve as a heat shield and heat sink. When used with a hybrid inflator, the retainer bracket has a formed air distribution passage allowing the output gas to be equally distributed into the folded air cushion and reducing the possibility that the stress of localized high velocity gas discharge would degrade the air cushion.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.